A beautiful tree in much too small a place. You might see if the local parks or public gardens will take it as a donation. Some nurseries or independent garden centers will buy it from you, and even dig it up for you. As for keeping it in a large container and pruning it, that is possible, but will take a fair amount of skill to keep it looking like a Christmas tree. I would read up on bonsai techniques, with an eye to using the methods to keep its shape, rather than making it look like an elfin forest hardcase! :)

I think your other idea of replacing it with a dwarf conifer would be preferable to trying to keep this one restricted -I hope you can find someone who would be glad to have it.If will need great care moving though as its rather big now. Don't try to transplant it during the growing season. Very early spring is the best time to move evergreens.

There are so many small ones it would be better if you just Google Dwarf Conifers. Be aware though that although they grow very slowly the do get bigger in time so don't plant right up against the boundary..